Keeping tabs on groundwater is more important than ever. Most of the western United States is suffering the most extreme drought in 12 centuries, and climate change only promises to make things worse. Underground aquifers can provide lifelines for farmers and cities, but pumping them dry causes the earth to sag, which is called subsidence. This can create sinkholes and destroy infrastructure. But groundwater is hard to monitor; it’s sometimes located thousands of feet below the surface. That’s where satellites come in. Marketplace’s Meghan McCarty Carino speaks with Kyra Kim, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory, where they’ve created a model to track groundwater levels using two satellite systems.